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Abstract:

A handle for a wand of a vacuum cleaning appliance includes a handgrip
portion and a conduit for receiving an air flow. The handle includes an
aperture for admitting ambient air into the conduit. A first valve
occludes a first portion of the aperture, and a second valve occludes a
second portion of the aperture. A control mechanism moves the first and
second valves away from the aperture to admit ambient air into the
conduit. To reduce the force required to move the valves away from the
aperture, the control mechanism is configured to move the second valve
away from the second portion of the aperture before moving the first
valve away from the first portion of the aperture.

Claims:

1. A handle for a wand of a vacuum cleaning appliance, the handle
comprising: a handgrip portion; a conduit for receiving an airflow; at
least one aperture for admitting ambient air into the conduit; a first
valve for occluding a first portion of said at least one aperture, and a
second valve for occluding a second portion of said at least one
aperture; and a control mechanism for moving the first and second valves
away from said at least one aperture to admit ambient air into the
conduit, the control mechanism being configured to move the second valve
away from the second portion of said at least one aperture before moving
the first valve away from the first portion of said at least one
aperture.

2. The handle of claim 1, wherein the control mechanism comprises a
manually operable actuator located on the handle for moving both of the
first and second valves away from said at least one aperture.

3. The handle of claim 2, wherein the actuator is located on the handgrip
portion of the handle.

4. The handle of claim 3, wherein the actuator is moveable relative to
the handgrip portion of the handle.

5. The handle of claim 3, wherein the actuator is depressible towards the
conduit.

6. The handle of claim 1, wherein the control mechanism is at least
partially located within the handgrip portion of the handle.

7. The handle of claim 1, wherein each of the valves is biased towards
its respective portion of said at least one aperture.

8. The handle of claim 1, wherein the first portion is larger than the
second portion.

9. The handle of claim 1, wherein the control mechanism comprises a
driven member connected to the actuator for moving the first and second
valves away from said at least one aperture.

10. The handle of claim 9, wherein the control mechanism is configured to
urge the second valve against the driven member.

11. The handle of claim 9, wherein the first valve is normally spaced
from the driven member.

12. The handle of claim 1, wherein the first portion extends at least
partially about the second portion.

13. The handle of claim 1, wherein the second valve is supported at least
partially by the first valve to occlude the second portion of the
aperture.

14. The handle of claim 13, wherein the first valve comprises an
additional aperture, and wherein the second valve is configured to move
away from the additional aperture in response to operation of the second
actuator to admit ambient air into the conduit though the additional
aperture and the second portion of said at least one aperture.

15. The handle of claim 14, wherein the additional aperture is located
centrally in the first valve.

16. The handle of claim 1, wherein the valves are located beneath the
handgrip portion of the handle.

17. A wand comprising the handle of claim 1.

18. A vacuum cleaning appliance comprising the wand of claim 17.

Description:

REFERENCE TO RELATED APPLICATIONS

[0001] This application is a national stage application under 35 USC 371
of International Application No. PCT/GB2011/050293, filed Feb. 15, 2011,
which claims the priority of United Kingdom Application No. 1003605.1,
filed Mar. 4, 2010, and United Kingdom Application No. 1101952.8, filed
Feb. 4, 2011, the entire contents of which are incorporated herein by
reference.

FIELD OF THE INVENTION

[0002] The present invention relates to a handle for a wand of a vacuum
cleaning appliance.

BACKGROUND OF THE INVENTION

[0003] A vacuum cleaner typically comprises a main body containing dirt
and dust separating apparatus, a floor tool connected to the main body
and having a suction opening, and a motor-driven fan unit for drawing
dirt-bearing air through the suction opening. The suction opening is
directed downwardly to face the floor surface to be cleaned. The
dirt-bearing air is conveyed to the separating apparatus so that dirt and
dust can be separated from the air before the air is expelled to the
atmosphere. The separating apparatus can take the form of a filter, a
filter bag or, as is known, a cyclonic arrangement. The present invention
is not concerned with the nature of the separating apparatus and is
therefore applicable to vacuum cleaners utilizing any of the above
arrangements or another suitable separating apparatus.

[0004] A driven agitator, usually in the form of a brush bar, is supported
in the floor tool so as to protrude by a small extent from the suction
opening. The brush bar is activated mainly when the vacuum cleaner is
used to clean carpeted surfaces. The brush bar comprises an elongate
cylindrical core bearing bristles which extend radially outward from the
core.

[0005] Rotation of the brush bar may be driven by an electric motor
powered by a power supply derived from the main body of the cleaner, or
by an air turbine assembly driven by an air flow into the floor tool. The
rotation of the brush bar causes the bristles to sweep along the surface
of the carpet to be cleaned to loosen dirt and dust, and pick up debris.
The suction of air generated by the fan unit of the vacuum cleaner causes
air to flow underneath the floor tool and around the brush bar to help
lift the dirt and dust from the surface of the carpet and then carry it
from the suction opening through the floor tool towards the separating
apparatus.

[0006] The air flow into the suction opening may be varied by a user
during a cleaning operation. For example, it is known to provide a bleed
valve on a wand to which the floor tool is connected to allow ambient air
to be admitted into the air flow passing from the floor tool to the
separating apparatus. When the bleed valve is opened by the user there is
a decrease in the rate at which air enters the floor tool through the
suction opening, and so there is a decrease in the level of suction at
the floor tool. This can enable items which may have become stuck within
the floor tool to be dislodged, and can enable a user to clean relatively
delicate items, such as curtains or other fabrics, without the fabric
becoming lodged within the floor tool.

SUMMARY OF THE INVENTION

[0007] In a first aspect, the present invention provides a handle for a
wand of a vacuum cleaning appliance, the handle comprising a handgrip
portion, a conduit for receiving an airflow, at least one aperture for
admitting ambient air into the conduit, a first valve for occluding a
first portion of said at least one aperture, and a second valve for
occluding a second portion of said at least one aperture, a control
mechanism for moving the first and second valves away from said at least
one aperture to admit ambient air into the conduit, the control mechanism
comprising a first manually operable actuator located on the handle for
moving both of the first and second valves away from said at least one
aperture, and a second manually operable actuator located on the handle
for moving only one of the first and second valves away from its
respective portion of said at least one aperture.

[0008] The at least one aperture may comprise first and second apertures.
In this case, the first portion of said at least one aperture may
comprise the first aperture, and the second portion of said at least one
aperture may comprise the second aperture. The first and second apertures
may be spaced along the conduit of the handle. The first aperture and the
second aperture may be spaced apart, separated by, for example part of
the outer wall of the conduit.

[0009] Alternatively, the first and second apertures may be located next
to one another without being separated by part of the outer wall of the
conduit. In this case, the at least one aperture may be considered to
comprise a single aperture, with the first valve being arranged to
occlude a first portion of the aperture and the second valve being
arranged to occlude a second portion of the aperture.

[0010] The provision of first and second valves for admitting air into the
conduit of the handle can allow the user to vary the rate at which air is
admitted into the conduit, and therefore the degree of suction at a floor
tool of the cleaning appliance. The location of two actuators on the
handle for moving only one or both of the valves away from their
respective portions of said at least one aperture can allow the user to
vary the degree of suction using the hand which is grasping the handle,
thereby improving user operability.

[0011] The first actuator is preferably located on the handgrip portion of
the handle, and so may be operable using a thumb of a hand which is
grasping the handgrip portion of the handle. The first actuator may be in
the form of a button which is operable by the user to actuate the
movement of the valves, for example using an electrical drive system.
Alternatively, the first actuator may be moveable relative to the
handgrip portion of the handle to actuate the control mechanism. For
example, the first actuator may be depressible towards the conduit, and
may be arranged to slide relative to the handgrip portion. Where the
control mechanism is in the form of an electrical drive system, the
second actuator may also be in the form of a button which is operable by
the user to actuate the movement of, for example, only the second valve.
Alternatively, the second actuator may also be moveable relative to the
handgrip portion to actuate the movement of the second valve. The second
actuator may be located adjacent the first actuator. However, to reduce
the risk of the user moving accidentally both valves when it is only
desired to move one of the valves, the second actuator is preferably
spaced from the first actuator. In a preferred embodiment, the second
actuator is located beneath the handgrip portion of the handle, and is
preferably in the form of a trigger which is actuable by a user to pull
said one of the first and second valves away from its respective portion
of said at least one aperture. Making the movement of the second actuator
relative to the handle different from that of the first actuator relative
to the handle can further reduce the risk of the user accidentally
operating the wrong valve.

[0012] The control mechanism is preferably at least partially housed
within the handgrip portion of the handle. Each of the valves is
preferably biased towards its respective portion of said at least one
aperture so that both portions are occluded automatically when an
actuator is released by the user.

[0013] The at least one aperture is preferably located beneath the
handgrip portion.

[0014] As mentioned above, the at least one aperture may comprise a single
aperture, with each valve being arranged to occlude a respective portion
of the aperture. The first valve may be arranged to occlude a relatively
large first portion of the aperture, and the second valve may be arranged
to occlude a relatively small second portion of the aperture. The
portions of the aperture may be disposed in any convenient arrangement.
For example, the portions of the aperture may be located side by side.
Alternatively, the first portion of the aperture may at least partially
extend about the second portion of the aperture. For example, the first
portion of the aperture may surround the second portion of the aperture.

[0015] To reduce the force that is required to move the first valve away
from its portion of the at least one aperture, the control mechanism may
be configured to, in response to operation of the first actuator, move
the second valve away from the second portion of said at least one
aperture before moving the first valve away from the first portion of
said at least one aperture. This movement of the second, preferably
relatively small, valve allows an amount of ambient air to be bled into
the conduit to reduce the pressure differential across the first,
preferably relatively large, valve, and therefore reduce the force
required to move the first valve away from the first portion of the at
least one aperture.

[0016] The control mechanism preferably comprises a driven member
connected to the first actuator for moving the first and second valves
away from said at least one aperture. The control mechanism preferably
comprises means such as a spring or other resilient member for urging the
second valve against the driven member so that the second valve moves
with the driven member upon operation of the first actuator. On the other
hand, the first valve is preferably normally spaced from the driven
member so that the first valve is not immediately moved by the driven
member upon operation of the first actuator. This can ensure that the
second valve is moved away from its respective portion of said at least
one aperture, and therefore that air has been bled into the conduit,
before the driven member engages the first valve to effect movement of
the first valve away from its respective portion of the at least one
aperture.

[0017] In a second aspect, the present invention provides a handle for a
wand of a vacuum cleaning appliance, the handle comprising a handgrip
portion, a conduit for receiving an airflow, at least one aperture for
admitting ambient air into the conduit, a first valve for occluding a
first portion of said at least one aperture, and a second valve for
occluding a second portion of said at least one aperture, and a control
mechanism for moving the first and second valves away from said at least
one aperture to admit ambient air into the conduit, the control mechanism
being configured to move the second valve away from the second portion of
said at least one aperture before moving the first valve away from the
first portion of said at least one aperture.

[0018] As mentioned above, the portions of the at least one aperture may
be located side by side or otherwise next to each other without the
portions being separated by part of the outer wall of the conduit or any
other feature of the handle so that the conduit comprises a single
aperture. This can provide for a compact arrangement of the valves of the
handle. For example, the first portion of the aperture may at least
partially extend about, and may surround, the second portion of the
aperture. The first valve may be supported by the periphery of the first
portion of the aperture, as defined by the conduit of the handle, when
the first valve occludes the first portion of the aperture. Where the
first portion at least partially extends about the second portion, the
second valve will at least partially extend about the first valve, and so
the second valve may be conveniently at least partially supported by the
first valve when the second valve occludes the second portion of the
aperture. The first valve may comprise an additional aperture, and the
second valve may be configured to move away from the additional aperture
in response to operation of the second actuator to admit ambient air into
the conduit though the additional aperture and the second portion of said
at least one aperture. This additional aperture may be located on the
periphery of the first valve, but in a preferred embodiment the
additional aperture is located centrally in the first valve.

[0019] In a third aspect the present invention provides a handle for a
wand of a vacuum cleaning appliance, the handle comprising a handgrip
portion, a conduit for receiving an airflow, an aperture for admitting
ambient air into the conduit, a first valve for occluding a first portion
of the aperture, and a second valve for occluding a second portion of the
aperture, and a control mechanism for moving the first and second valves
away from the aperture to admit ambient air into the conduit, wherein the
second valve is supported at least partially by the first valve to
occlude the second portion of the aperture.

[0020] In a fourth aspect the present invention provides a wand comprising
a handle as aforementioned. The wand may form part of a vacuum cleaning
appliance comprising a vacuum cleaning head connected to the wand. The
head preferably has a first state and a second state, and comprises a
control assembly for controlling the state of the head in response to
operation of the control mechanism of the handle. The control assembly
preferably comprises a pressure chamber having an interior volume in
fluid communication with the conduit, the pressure chamber being moveable
from an expanded configuration to a contracted configuration in response
to a pressure difference between the interior volume and ambient air, and
biased towards the expanded configuration. The control assembly
preferably also comprises a chamber control mechanism for allowing the
pressure chamber to move to the contracted configuration in response to a
first operation of the control mechanism to place the head in one of the
first and second states, and for preventing the pressure chamber from
returning to the contracted configuration in response to a second
operation of the control mechanism to place the head in the other of the
first and second states.

[0021] By sequentially operating the control mechanism of the handle to
cause the air pressure in the conduit to fluctuate between upper and
lower values, the user can toggle the state of the chamber control
mechanism to selectively allow or prevent the pressure chamber for
adopting its contracted configuration, thereby selectively switching the
state of the head. The change in the configuration of the pressure
chamber can vary, for example, the state or position of an agitator for
agitating dirt from a surface to be treated, a speed of rotation of such
an agitator, or the relative positions of two other parts of the cleaning
head.

[0022] The agitator may be in the form of a brush having a plurality of
bristles, filaments or other surface agitating elements. The agitator may
be moveable relative to the housing between active and inactive states,
which correspond to the first and second states of the head,
respectively. Alternatively, the agitator may be rotatable relative to
the housing in its active state, and generally stationary relative to the
housing in its inactive state. The agitator may comprise a disc or other
generally planar member which is rotatable relative to the housing, or it
may comprises an elongate brush bar having agitating elements extending
radially outwardly therefrom.

[0023] The head preferably comprises a drive mechanism for rotating the
agitator relative to the housing, the control assembly being arranged to
deactivate the drive mechanism in response to the first operation of the
control mechanism, and to re-activate the drive mechanism in response to
the second operation of the control mechanism. The drive mechanism may
comprise a motor which is deactivated in response to the first operation
of the control mechanism. Alternatively, the drive mechanism may comprise
a drive belt which is moved from a pulley or gear to an idler to place
the agitator in its inactive state, or a clutch which is placed in either
an engaged position or a disengaged position to change the state of the
actuator.

[0024] As another alternative, the drive mechanism may comprise an air
turbine assembly comprising an impeller for driving the agitator, with
the control assembly being arranged to inhibit rotation of the impeller
to change the state of the agitator. For example a braking system may be
fitted to the drive shaft of the impeller, with the control assembly
being arranged to deploy the braking system to engage the drive shaft or
a braking surface extending about the drive shaft to reduce the speed of
rotation of the impeller. Alternatively, a clutch may be provided for
selectively disengaging the drive shaft from the agitator. Preferably
though, the control assembly is arranged to inhibit air flow to the
impeller to stop the rotation of the impeller, thereby placing the
agitator in an inactive state. The head may comprise a turbine air inlet,
separate from the suction opening, for admitting a second air flow to the
turbine assembly, and so the control assembly may comprise a closure
member which is moveable between an open position and a closed position
for substantially closing the turbine air inlet to inhibit the flow of
air to the impeller. The closure member preferably comprises a seal for
sealing the turbine air inlet when the closure member is in the closed
position. The closure member is preferably biased towards the open
position, which can assist in moving the pressure chamber from the
contracted configuration towards the expanded configuration when the
control mechanism is operated.

[0025] Preferably, the duct comprises an entrainment chamber in which the
air flow from the suction opening merges with the air flow from the
turbine assembly. The pressure chamber may be connected to the airflow
path immediately downstream from the entrainment chamber. Alternatively,
the pressure chamber may be connected to the airflow path via a turbine
chamber housing the turbine assembly. For example, the turbine assembly
may be located within a turbine chamber through which the second air flow
passes from the turbine air inlet to the duct, and so is in fluid
communication with the duct, and the control mechanism may comprise a
duct which extends from the turbine chamber to the pressure chamber.

[0026] The chamber control mechanism preferably has a first state for
preventing the pressure chamber from adopting the contracted
configuration, and a second state for allowing the pressure chamber to
adopt the contracted configuration, the chamber control mechanism being
arranged to change between the first and second states in response to an
increase in the interior volume of the pressure chamber. The chamber
control mechanism is preferably arranged to adopt the first state when
there is substantially no pressure difference between the interior volume
and the ambient air, for example when the vacuum cleaning appliance is
switched off. As a result, each time the vacuum cleaning appliance is
switched on, the head will always be in a default one of the first and
second states, for example in a state in which an agitator is in an
active state for agitating a floor surface, to provide certainty for the
user.

[0027] The pressure chamber preferably comprises a first chamber section
and a second chamber section which is moveable relative to the first
chamber section. The first chamber section is preferably connected to a
housing of the head. The first chamber section and the second chamber
section may be connected by an annular seal to allow the second chamber
section to move relative to the first chamber section while maintaining
an air-tight seal between the sections of the pressure chamber. In this
case, the movement of the second chamber section relative to the first
chamber section actuates the control assembly to change the state of the
head. The actuation of the control assembly may be effected by a
non-contact technique, for example using a magnetic, electrical or
optical technique for actuating the control assembly based on the
relative positions between the first and second chamber sections. The
control assembly may comprise an actuator connected to the second chamber
section for actuating the change in the state of the head. For example,
the control assembly may comprise a first arm connected to the second
chamber section, and a second arm connected to the actuator, with the
first arm being connected, either directly or indirectly, to the second
arm. The first arm is preferably moveable relative to the second arm when
the control mechanism is in the first state so that movement of the
second chamber section relative to the first chamber section does not
actuate the actuator. The control mechanism must then be placed in the
second state to allow the pressure chamber to adopt its contracted
configuration before the first arm is able to move the second arm to
actuate the actuator. The pressure chamber may be located on the opposite
side of the duct to the actuator, and so the arms may extend over, or
beneath, the duct.

[0028] The pressure chamber may be formed from material which is
internally biased or otherwise constructed to urge the pressure chamber
towards its expanded configuration. Preferably though, the pressure
chamber comprises at least one spring for urging the pressure chamber
towards its expanded configuration. The second chamber section is
preferably biased away from the first chamber section.

[0029] The pressure chamber may comprise two springs for urging the
pressure chamber towards its expanded configuration. The first spring may
be arranged to control the switching of the chamber control mechanism
between its first and second states, whereas the second spring may be
arranged to urge the chamber control mechanism into its first state when
the pressure difference between the interior volume and the ambient air
decreases to zero. For example, the pressure chamber may comprise an
intermediary member located between the first and second chamber
sections, a first spring for biasing the intermediary member away from
the first chamber section, and a second spring for biasing the second
chamber section away from the intermediary member. The chamber control
mechanism may extend about the intermediary member. The chamber control
mechanism may conveniently be formed with a stop for restricting the
movement of the intermediary member away from the first chamber section
under the action of the first spring.

[0030] The two springs are preferably axially aligned. The first spring
preferably has a higher spring constant than the second spring so that
the second spring remains in a compressed configuration while the first
spring effects the transition of the chamber control mechanism between
the first and second states.

[0031] The chamber control mechanism preferably comprises a track carrier
connected to the first chamber section, and a track follower moveable
with the second chamber section for movement relative to the track
carrier, the track carrier comprising a track for guiding movement of the
track follower relative to the track carrier as the configuration of the
pressure chamber varies. Both of the track carrier and the track follower
may be located within the pressure chamber. The track follower preferably
extends about the track carrier, which is preferably cylindrical in
shape. The track follower is preferably retained by the second chamber
section so that the track follower is moveable both axially and
rotationally relative to the track carrier. The track follower is
preferably rotatable relative to the second chamber section as the second
chamber section moves towards or away from the first chamber section
depending on the balance of the forces applied thereto due to the spring
constant of the springs and the pressure differential thereacross.

[0032] A transition of the chamber control mechanism from the first state
to the second state corresponds to a movement of the track follower
relative to the track carrier from a first position in which, due to the
shape of the track, the second chamber section is unable to move towards
the first chamber section, under the force applied thereto due to the
pressure differential across the second chamber section, to actuate the
actuator, to a second position in which the shape of the track allows the
track follower subsequently to move along the track carrier so that the
pressure chamber contracts sufficiently to cause the actuator to change
the state of the agitator. This movement of the track follower from the
first position to the second position results from an increase in the
interior volume of the pressure chamber due to the user opening the valve
to admit air into an airflow path extending from the suction opening to a
fan unit.

[0033] The track follower may adopt a range of different positions
relative to the track carrier when the chamber control mechanism is in
each of the first and second states. The chamber control mechanism may be
considered to be in a first state when the track follower is in a
position relative to the track carrier from which the pressure chamber is
unable to adopt the contracted configuration when the pressure
differential across the second chamber section is relatively high, and to
be in a second state when the track follower is in a position relative to
the track carrier from which the pressure chamber is able to adopt the
contracted configuration when the pressure differential across the second
chamber section is relatively high.

[0034] Features described above in connection with the first aspect of the
invention are equally applicable to any of the second to fourth aspects
of the invention, and vice versa.

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] An embodiment of the present invention will now be described, by
way of example only, with reference to the accompanying drawings, in
which:

[0036]FIG. 1 is a front left perspective view, from above, of a floor
tool for a vacuum cleaning appliance;

[0037]FIG. 2 is a front right perspective view, from above, of the floor
tool of FIG. 1;

[0047] FIGS. 11(a) to (f) illustrate a series of external views of a track
carrier of the control assembly, illustrating various different positions
of a pin of a track follower of a control mechanism of the control
assembly relative to the track carrier;

[0048] FIG. 12(a) is a similar view to FIG. 9(a), but with the pressure
chamber in a first partially contracted configuration;

[0049] FIG. 12(b) is a similar view to FIG. 9(b) when the pressure chamber
is in the first partially contracted configuration;

[0050] FIG. 13(a) is a front right perspective view, from above, of the
floor tool of FIG. 1 connected to one end of a wand;

[0051] FIG. 13(b) is a perspective view of a vacuum cleaning appliance
including the wand and floor too of FIG. 13(a);

[0052] FIG. 14(a) is a front left perspective view, from above, of a
handle connected to the wand of FIG. 13(a);

[0053] FIG. 14(b) is a front right perspective view, from above, of the
handle, with part of the handle removed;

[0054] FIG. 14(c) is a right side view of the handle, with the valves of
the handle in a closed position;

[0055] FIG. 14(d) is a side sectional view of the handle, with the valves
of the handle in the closed position;

[0056] FIG. 15(a) is a right side view of the handle, with the valves of
the handle in an open position;

[0057] FIG. 15(b) is a side sectional view of the handle, with the valves
of the handle in the open position;

[0058] FIG. 16(a) is a similar view to FIG. 9(a), but with the pressure
chamber in a second partially contracted configuration;

[0059] FIG. 16(b) is a similar view to FIG. 9(b) when the pressure chamber
is in the second partially contracted configuration;

[0060] FIG. 17(a) is a similar view to FIG. 9(a), but with the pressure
chamber of the floor tool in a first, fully contracted configuration;

[0061] FIG. 17(b) is a similar view to FIG. 9(b) when the pressure chamber
is in the first, fully contracted configuration;

[0062] FIG. 18(a) is a similar view to FIG. 9(a), but with the pressure
chamber of the floor tool in a second, fully contracted configuration;
and

[0063] FIG. 18(b) is a similar view to FIG. 9(b) when the pressure chamber
is in the second, fully contracted configuration.

DETAILED DESCRIPTION OF THE INVENTION

[0064] FIGS. 1 to 4 illustrate an embodiment of a floor tool 10 for a
vacuum cleaning appliance. In this embodiment, the floor tool 10 is
arranged to be connectable to a wand or hose of a cylinder vacuum
cleaning appliance. The floor tool 10 comprises a main body 12 and a
conduit 14 connected to the body 12. The main body 12 comprises
substantially parallel side walls 16, 18 extending forwardly from
opposite ends of a rear section 20 of the main body 12, and a moveable
section 22 located between the side walls 16, 18 of the main body 12. In
this embodiment the moveable section 22 is rotatably connected to the
main body 12 for rotation about an axis A which extends generally
orthogonally between the side walls 16, 18 of the main body 12.

[0065] The moveable section 22 comprises a curved upper wall 24, a lower
plate, or sole plate 26, and two side walls 28, 30 which connect the sole
plate 26 to the upper wall 24. The side walls 28, 30 are located between
the side walls 16, 18 of the main body 12, with each side wall 28, 30
being located adjacent and substantially parallel to a respective one of
the side walls 16, 18 of the main body 12. In use, the sole plate 26
faces the floor surface to be cleaned and, as described in more detail
below, engages the surface of a carpeted floor surface. The sole plate 26
comprises a leading section 32 and a trailing section 34 located on
opposite sides of a suction opening 36 through which a dirt-bearing air
flow enters the floor tool 10. The suction opening 36 is generally
rectangular in shape, and is delimited by the side walls 28, 30, a
relatively long front wall 38 and a relatively long rear wall 40 which
each upstand from the bottom surface of the sole plate 26. These walls
also delimit the start of a suction passage through the main body 12 of
the floor tool 10.

[0066] The sole plate 26 comprises two working edges for agitating the
fibres of a carpeted floor surface as the floor tool 10 is manoeuvred
over such a surface. A front working edge 42 of the sole plate 26 is
located at the intersection between the front wall 38 and the bottom
surface of the leading section 32 of the sole plate 26, and extends
substantially uninterruptedly between the side walls 28, 30. A rear
working edge 44 of the sole plate 26 is located at the intersection
between the rear wall 40 and the bottom surface of the trailing section
34 of the sole plate 26, and extends substantially uninterruptedly
between the side walls 28, 30. At least the front working edge 42 is
preferably relative sharp, preferably having a radius of curvature less
than 0.5 mm.

[0067] A front bumper 46 is over-moulded on to the moveable section 22,
and is located between the upper wall 24 and the sole plate 26.

[0068] To prevent the working edges 42, 44 from scratching or otherwise
marking a hard floor surface as the floor tool 10 is manoeuvred over such
a surface, the floor tool 10 comprises at least one surface engaging
support member which serves to space the working edges 42, 44 from a hard
floor surface. In this embodiment, the floor tool 10 comprises a
plurality of surface engaging support members which are each in the form
of a rolling element, preferably a wheel. A first pair of wheels 48 is
rotatably mounted within a pair of recesses formed in the leading section
32 of the sole plate 26, and a second pair of wheels 50 is rotatably
mounted within a pair of recesses formed in the trailing section 34 of
the sole plate 26. As illustrated in FIG. 4, the wheels 48, 50 protrude
downwardly beyond the working edges 42, 44 so that when the floor tool 10
is located on a hard floor surface H with the wheels 48, 50 engaging that
surface, the working edges 42, 44 are spaced from the hard floor surface.

[0069] During use, a pressure difference is generated between the air
passing through the floor tool 10 and the external environment. This
pressure difference generates a force which acts downwardly on the floor
tool 10 towards the floor surface. When the floor tool 10 is located on a
carpeted floor surface, the wheels 48, 50 are pushed into the fibres of
the carpeted floor surface under the weight of the floor tool 10 and the
force acting downwardly on the floor tool 10. The thickness of the wheels
48, 50 is selected so that the wheels 48, 50 will readily sink into the
carpeted floor surface to bring at least the working edges 42, 44 of the
sole plate 26 into contact with the fibres of the floor surface. The
thickness of the wheels 48, 50 is preferably less than 10 mm, more
preferably less than 5 mm, to ensure that the wheels 48, 50 sink between
the fibres of a carpeted floor surface. The bottom surface of the leading
section 32 of the sole plate 26 is inclined upwardly and forwardly
relative to a plane passing through the working edges 42, 44 of the sole
plate 26. As a result, in use, the leading section 32 can guide the
fibres of a rug or deeply piled carpeted floor surface beneath the floor
tool 10 and into the suction opening 36 as the floor tool 10 is
manoeuvred forwardly over that floor surface, thereby lowering the
resistance to forward motion of the floor tool 10 over the floor surface.
The bottom surface of the trailing section 34 of the sole plate 26 is
inclined upwardly and rearwardly relative to the plane passing through
the working edges 42, 44 of the sole plate 26. As a result, in use, the
trailing section 34 can guide the fibres of a rug or deeply piled
carpeted floor surface beneath the floor tool 10 and into the suction
opening 36 as the floor tool 10 is manoeuvred rearwardly over that floor
surface, thereby lowering the resistance to the rearward motion of the
floor tool 10 over the floor surface.

[0070] As the floor tool 10 is pulled backwards over a carpeted floor
surface by a user, there is a tendency for the user to raise the rear
section 20 of the main body 12 of the floor tool 10. However, the
rotatable connection of the moveable section 22 to the main body 12
allows the sole plate 26 to pivot relative to the main body 12 to
maintain the working edges 42, 44 in contact with the floor surface. This
can enable a seal to be maintained between the working edges 42, 44 and
the floor surface during use, which can improve the pick up performance
of the floor tool. Clockwise rotation of the moveable member 22 relative
to the main body 12 (as viewed along axis A in FIG. 4) is restricted
through the abutment of upwardly facing surfaces 52 located toward the
ends of the bumper 46 of the moveable member 22 with downwardly facing
surfaces 54 located towards the front of the side walls 16, 18 of the
main body 12. Anticlockwise rotation of the moveable member 22 relative
to the main body 12 is restricted through the abutment of the upper
surface 56 of the trailing section 34 of the sole plate 26 with the
bottom surfaces 58 of the side walls 16, 18 of the main body 12.

[0071] Returning to FIG. 3, the floor tool 10 further comprises an
agitator 60 for agitating the fibres of a carpeted floor surface. In this
embodiment the agitator 60 is in the form of a brush bar which is located
within the suction passage and is rotatable relative to the main body 12
about axis A. The agitator 60 comprises an elongate body 62 which rotates
about the longitudinal axis thereof The body 62 passes through apertures
formed in the side walls 28, 30 of the moveable member 22 so that one end
of the body 62 can be supported by a removable portion 64 of the side
wall 18 of the main body 12 for rotation relative to the main body 12,
whereas the other end of the body 62 can be supported and rotated by a
drive mechanism which is described in more detail below.

[0072] The agitator 60 further comprises surface engaging elements which
in this embodiment are in the form of bristles 66 protruding radially
outwardly from the body 62. The bristles 66 are arranged in a plurality
of clusters, which are preferably arranged at regular intervals along the
body 62 in one or more helical formations. The bristles 66 are preferably
formed from an electrically insulating, plastics material. Alternatively,
at least some of the bristles 66 may be formed from a metallic or
composite material in order to discharge any static electricity residing
on a carpeted floor surface.

[0073] FIGS. 5 to 8 and 9(a) illustrate a drive mechanism 70 for rotating
the agitator 60 relative to the main body 12 of the floor tool 10. The
drive mechanism 70 comprises an air turbine assembly 72 located within a
turbine chamber 74. The turbine chamber 74 comprises an inner section 76
which is connected to, and is preferably integral with, one side of the
rear section 20 of the main body 12, and an outer section 78 connected to
the end of the inner section 76. The outer section 78 comprises an air
inlet 80 through which an air flow may be drawn into the turbine chamber
74 through operation of a fan unit of the vacuum cleaning appliance to
which the floor tool 10 is connected. A porous cover 81, such as a mesh
screen, may be disposed over the air inlet 80 to inhibit the ingress of
dirt and dust into the turbine chamber 74.

[0074] Air passing through the turbine chamber 74 is exhausted into an air
duct 82 extending rearwardly from the rear section 20 of the main body 12
towards the conduit 14. The air duct 82 may be considered to form part of
the suction passage through the main body 12. The air duct 82 comprises
an inlet section 84 for receiving an air flow from an air outlet 86 of
the main body 12, and a side inlet 88 for receiving an air flow exhausted
from the turbine chamber 74. A mesh screen 89 may be provided adjacent
the side inlet 89 to inhibit the ingress of dirt into the turbine chamber
74 from the side inlet 88. The inlet section 84 of the air duct 82
provides a flow restriction for throttling the air flow from the main
body 12, and so the size of the outlet orifice of the inlet section 84
determines the ratio of the flow rate of air entering the floor tool 10
through the suction opening 36 to the flow rate of air entering the floor
tool through the air inlet 80 of the turbine chamber 74. For example,
when the outlet orifice is relatively small the flow rate of the air
entering the floor tool 10 through the air inlet 80 will be greater than
that entering the floor tool 10 through the suction opening 36. This will
result in the agitator 60 being driven to rotate at a relatively high
speed, but with a relatively low level of suction at the suction opening
36. On the other hand, when the outlet orifice is relatively large the
flow rate of the air entering the floor tool 10 through the air inlet 80
will be smaller than that entering the floor tool 10 through the suction
opening 36. This will result in the agitator 60 being driven to rotate at
a relatively low speed, but with a relatively high level of suction at
the suction opening 36. Therefore, the shape of the inlet section 84 can
be chosen to provide the desired combination of agitator rotational speed
and suction at the suction opening 36.

[0075] The air flow exhausted from the turbine chamber 74 merges with the
air flow exhausted from the main body 12 within an entrainment chamber 90
located immediately downstream from the inlet section 84 of the air duct
82. This prevents the generation of eddy currents or other air
circulating regions immediately downstream from the flow restriction
defined by the inlet section 84 of the duct 82, and so reduces the
pressure losses within the floor tool 10.

[0076] The duct 82 has an outlet section 91 located downstream from the
entrainment chamber 90. The inlet orifice of the outlet section 91 of the
duct 82 is located opposite to the outlet orifice of the inlet section 84
of the duct 82, and has a greater cross-sectional area orthogonal to the
air flow therethrough than the outlet orifice of the inlet section 84 of
the duct 82. The outlet section 91 of the air duct 82 is connected to an
inlet section 92 of the conduit 14. The conduit 14 also comprises an
outlet section 94 which is connectable to a hose, wand or other duct of a
vacuum cleaning appliance, and a flexible duct 96 connected between the
inlet section 92 and the outlet section 94 of the conduit 14. The conduit
14 is supported by a pair of wheels 98.

[0077] The turbine assembly 72 comprises an impeller 100 integral with, or
mounted on, an impeller drive shaft 102 for rotation therewith. For
example, the impeller 100 may be moulded or pressed on to the impeller
drive shaft 102. The impeller 100 comprises a circumferential array of
equidistant impeller blades 104 arranged about the outer periphery of the
impeller 100. The impeller 100 may be a single piece or assembled from
two or more annular sections of sheet material each bearing an array of
impeller blades 104. These sections of sheet material may be brought
together, one over the other, to form the impeller 100, with the blades
of one annular section alternately arranged with the blades of the other
annular section.

[0078] The impeller drive shaft 102 is rotatably mounted in a stator 110
of the turbine assembly 72. The stator 110 comprises a first annular
array of stator blades 112 which is arranged circumferentially about the
outer periphery of an annular stator body 114 into which the impeller
drive shaft 102 is inserted. The stator body 114 has substantially the
same external diameter as the impeller 100, and the stator blades 112 are
substantially the same size as the impeller blades 104. The impeller
drive shaft 102 is supported within the bore of the stator body 114 by
bearings 116, 118 so that the impeller blades 104 are located opposite to
the stator blades 112. The stator body 114 is surrounded by a cylindrical
stator housing 120 which defines with the stator body 114 an annular
channel within which the stator blades 112 are located. The stator blades
112, stator body 114 and the stator housing 120 may be conveniently
formed as a single piece. An annular, resilient support member 122 forms
a seal between the outer surface of the stator housing 120 and the inner
surface of the turbine chamber 74. The elasticity of the support member
122 is selected to minimise the transmission of vibrations from the
turbine assembly 72 to the turbine chamber 74. The stator 110 further
comprises a nose cone 124 which is mounted over the end of the stator
body 114 which is remote from the impeller 100. The nose cone 124
includes a second annular array of stator blades 126 which is of a
similar size as, and located adjacent to, the first array of stator
blades 112. The outer surface of the nose cone 124 is shaped so as to
guide an air flow into the annular channel between the stator body 114
and the stator housing 120.

[0079] The stator housing 120 is connected to, and preferably integral
with, a cylindrical impeller housing 130, which defines with the impeller
100 an annular channel within which the impeller blades 104 are located.
The impeller housing 130 is in turn connected to, and is preferably
integral with, a turbine outlet conduit 134 which is mounted on the air
duct 82 so that the outlet of the turbine outlet conduit 134 surrounds
the side inlet 88 of the air duct 82. An annular sealing member 136 forms
a seal between the side inlet 88 of the air duct 82 and the turbine
outlet conduit 134.

[0080] The drive mechanism 70 further comprises a gear 140 mounted on the
side of the impeller 100 opposite to the impeller drive shaft 102 for
rotation with the impeller 100. A first belt 142 (shown in FIG. 7)
connects the gear 140 to a drive pulley 144 mounted on one end of a drive
shaft 146. To inhibit the ingress of dirt and dust within this part of
the drive mechanism 70, and to prevent user contact with the drive
mechanism 70, the first belt 142, the drive pulley 144 and the drive
shaft 146 are housed within drive housing 150. The drive housing 150 is
preferably integral with the impeller housing 130.

[0081] The drive shaft 146 is located within the rear section 20 of the
main body 12, and is substantially parallel to the axis A. The drive
shaft 146 is housed within drive shaft housing 152 which is preferably
integral with the drive housing 150. A first driven pulley 154 is
connected to the other end of the drive shaft 146. The first driven
pulley 154 is connected to a larger, second driven pulley 156 by a second
belt 158. A belt cover 160 extends partially about the second belt 158. A
drive dog 162 is mounted on one side of the second driven pulley 158 for
connection to the body 62 of the agitator 60.

[0082] Consequently, when an air flow is drawn through the turbine chamber
74 under the action of a motor-driven fan unit housed within a vacuum
cleaning appliance attached to the outlet section 94 of the conduit 14
the impeller 100 is rotated relative to the turbine chamber 74 by the air
flow. The rotation of the impeller 100 causes the drive pulley 142 to be
rotated by the first belt 144. The rotation of the drive pulley 142
rotates the drive shaft 146 and the first driven pulley 154, and the
rotation of the first driven pulley 154 causes the second driven pulley
156 to be rotated by the second belt 158. The rotation of the second
driven pulley 156 results in the rotation of the agitator 60 relative to
the main body 12.

[0083] The agitator 60 may be placed in an inactive state, in which the
agitator 60 is stationary relative to the main body 12, during operation
of the fan unit by selectively closing the entrance to the annular
channel located between the outer surface of the stator body 114 and the
stator housing 120 to inhibit air flow through the turbine chamber 74.
Inhibiting the air flow through the turbine chamber 74 prevents the
impeller 100 from rotating relative to the turbine chamber 74, which
prevents the drive mechanism 70 from rotating the agitator 60 relative to
the main body 12.

[0084] Returning to FIGS. 8 and 9(a), the turbine chamber 74 houses a
resilient turbine seal 170 for closing the entrance to the annular
channel to inhibit the air flow through the turbine chamber 74. The
turbine seal 170 is generally in the form of a sleeve which is connected
at one end thereof to the support member 122 and at the other end thereof
to an annular member 172 of a turbine chamber control assembly 174,
illustrated in FIG. 9(b). The outer surface of the turbine seal 170
passes, in turn, around the inner radial periphery, the outer end wall
and the outer radial periphery of the annular member 172 before being
connected to the annular member 172.

[0085] The control assembly 174 uses variation in air pressure within the
air duct 82 to effect the movement of the turbine seal 170 relative to
the turbine chamber 74. The annular member 172 thus provides an actuator
of the control assembly 174 for actuating the change in the state of the
agitator 60. The control assembly 174 comprises a pressure chamber 176
contained within a chassis 178 located on the opposite side of the air
duct 82 to the turbine chamber 74. The chassis 178 comprises an inner
section 180 which is connected to, and is preferably integral with, the
other side of the rear section 20 of the main body 12, and an outer
section 182 connected to the end of the inner section 180. The outer
section 182 of the chassis 178 includes a central aperture 184.

[0086] The pressure chamber 176 is placed in fluid communication with the
air duct 82 by a conduit 192 extending between the turbine chamber 74 and
the pressure chamber 176. While the conduit 192 may be connected directly
to the air duct 82, it is preferred to connect the conduit 192 to the
turbine chamber 74 as the presence of the mesh screens 81, 89 for
preventing the ingress of dirt into the turbine chamber 74 also prevents
dirt from entering the pressure chamber 176 when the air duct 82 is
connected to the turbine chamber 74. The pressure chamber 176 comprises a
first chamber section 194 and a second chamber section 196. The first
chamber section 194 comprises an end wall 198 which is located within the
central aperture 184 of the outer section 182 of the chassis 178 and an
annular outer side wall 200 which forms an interference fit with the
inner surface of the outer section 182 of the chassis 178 so that the
first chamber section 194 is secured to the chassis 178. The first
chamber section 194 further comprises a cylindrical, first inner side
wall 202 which is generally co-axial with the outer side wall 200, and a
cylindrical, second inner side wall 203 which is generally co-axial with
and surrounds the first inner side wall 202. The second chamber section
196 comprises an end wall 204 which is located opposite to, and generally
parallel with, the end wall 198 of the first chamber section 194, and a
stepped annular side wall 206.

[0087] A flexible, annular sealing member, which is preferably in the form
of a sleeve 208 formed from rubber or other material having similar
elastic properties, is connected to both the first chamber section 194
and the second chamber section 196 to form an airtight seal therebetween,
and to allow the second chamber section 196 to move relative to the first
chamber section 194 to vary the volume of the pressure chamber 176. One
end 210 of the sleeve 208 is connected to the outer surface of the outer
side wall 200 and the other end 212 of the sleeve 208 is connected to the
outer surface of the side wall 206 so that the sleeve 208 surrounds the
side walls 200, 206.

[0088] As discussed in more detail below, the pressure chamber 176 houses
a control mechanism for controlling the configuration of the pressure
chamber 176. The control mechanism comprises an annular track carrier 214
which is connected to the first chamber section 194. The track carrier
214 comprises an annular end wall 216, a generally cylindrical inner wall
218 and a generally cylindrical outer wall 220. A track 222 is located on
the outer surface of the outer wall 220. The track carrier 214 is
inserted between the inner walls 202, 203 of the first chamber section
194 so that the end wall 216 of the track carrier 214 is adjacent the end
wall 198 of the first chamber section 194. The track carrier 214 is
secured to the first chamber section 194 using a screw 224 or other
suitable connector.

[0089] The control assembly 174 further comprises a plurality of resilient
members, preferably in the form of helical compression springs, for
urging the pressure chamber 176 towards an expanded configuration, as
shown in FIGS. 8, 9(a) and 9(b). A first spring 226 has a first end which
engages the end wall 216 of the track carrier 214, and a second end which
extends about a tubular spring retainer 228 located between the first
chamber section 194 and the second chamber section 196. The spring
retainer 228 has a first annular spring abutment member 230 located on
the outer surface thereof, and which is normally spaced from the second
end of the first spring 226 when the pressure chamber 176 is in the
configuration illustrated in FIG. 9(a). The spring retainer 228 also has
a second annular spring abutment member 232 located on the inner surface
thereof. A second spring 234 has a first end which engages the end wall
204 of the second chamber section 196 and a second end which engages the
second annular spring abutment member 232. The second spring 234 thus
serves to urge the second chamber section 196 away from the spring
retainer 228, and therefore away from the first chamber section 194. The
spring retainer 228 comprises a plurality of slots which extend from the
second annular spring abutment member 232 towards an annular end of the
spring retainer 228 which is remote from the first annular spring
abutment member 230. A retainer clip 235 is secured to the end of the
inner wall 218 of the track carrier 214 by the screw 224. The spring
retainer 228 extends about the retainer clip 235. The retainer clip 235
comprises a pair of diametrically opposed lugs (not shown) which extend
radially outwardly therefrom, and which each passes through a respective
slot in the spring retainer 228. Engagement between the lugs and the
annular end of the spring retainer 228 prevents the spring retainer 228
from moving away from the track carrier 214 beyond the position
illustrated in FIG. 9(a).

[0090] Part of the outer wall 220 of the track carrier 214 is illustrated
in more detail in FIGS. 11(a) to 11(f). The track carrier 214 comprises a
track 222 in the form of a series of irregular, interconnected grooves
formed on the outer wall 220 of the track carrier 214. The track 222 is
divided into a plurality of interconnected track sections, in this
example five track sections, arranged circumferentially about the outer
wall 220 of the track carrier 214. A plurality of pins 236, in this
example five pins, is moveable along the track 222. The pins 236 are
mutually angularly spaced by an angle of 72° so that, at any given
instance, each pin 236 is located within a respective track section.
Returning to FIG. 9(a), the pins 236 are arranged about the inner surface
of an annular track follower 238 of the control mechanism. The track
follower 238 is retained by a retaining ring 240 attached to the second
chamber section 196 so that the track follower 238 is rotatable relative
to both the second chamber section 196 and the track carrier 214, and is
moveable axially relative to the track carrier 214. The track follower
238 is urged against the retaining ring 240 by an annular disc 242, which
is in turn urged against the track follower 238 by a third spring 244
disposed between the annular disc 242 and the second chamber section 196.

[0091] Returning to FIG. 9(b), the control assembly 174 comprises a
plurality of interconnected arms 250, 252 for connecting the second
chamber section 196 to the annular member 172. Two first arms 250 are
each connected at one end thereof to a respective one of two
diametrically opposing locations on the end wall 204 of the second
chamber section 196. Each of the first arms 250 extends over the upper
surface of the air duct 82 towards the turbine assembly 72. Each first
arm 250 has a locally enlarged end portion 254. Two second arms 252 are
each connected at one end thereof to a respective one of two
diametrically opposing locations on the annular member 172. Each second
arm 252 extends over the turbine assembly 72, the air duct 82 and the
first arm 250 towards the pressure chamber 176. The ends of the second
arms 252 which are remote from the annular member 172 are connected by an
arcuate connector 256. A slot 258 is located towards the other end of
each second arm 252 for retaining the end portion 254 of a respective
first arm 250 while permitting relative movement between the first arms
250 and the second arms 252. The second arms 252 are biased away from the
pressure chamber 176 by a fourth spring 260 so that when the fan unit of
the vacuum cleaning appliance is switched off, the fourth spring 260
urges the turbine seal 170 towards an expanded configuration illustrated
in FIGS. 8 and 9(a), in which the inner surface of the turbine seal 170
is spaced from the outer surface of the nose cone 124 to permit air flow
through the turbine chamber 74. The fourth spring 260 is located between
the outer section 182 of the chassis 178 and an annular spring retainer
262 forming part of the connector 256.

[0092] The conduit 192 may be formed from a plurality of connected pipes
or tubes. With reference to FIG. 10, the conduit 192 comprises an inlet
pipe 270 which is integral with the turbine outlet conduit 134 and in
fluid communication with the turbine chamber 74. The end of the inlet
pipe 270 is inserted into one end of a connecting tube 272 which passes
beneath the entrainment chamber 90 and the inlet 84 of the air duct 82.
The other end of the connecting tube 272 received the end of an outlet
pipe 274 of the conduit 192. The outlet pipe 274 is integral with the
first chamber section 194 of the pressure chamber 176. As a result, the
air pressure within the pressure chamber 176 will be substantially equal
to the air pressure in the turbine chamber 74, which will in turn
fluctuate with variations in the air pressure in the air duct 82. As the
chassis 178 is not hermetically sealed, the air pressure surrounding the
pressure chamber 176 will be maintained at or around atmospheric
pressure.

[0093] As mentioned above, FIGS. 8, 9(a) and 9(b) illustrate the
configuration of the control assembly 174 when the floor tool 10 is
disconnected from a vacuum cleaning appliance, or when the vacuum
cleaning appliance is switched off so that there is no air flow generated
by the fan unit of the appliance. In this configuration, the air pressure
within the pressure chamber 176 is the same as the air pressure outside
the pressure chamber 176. The two springs 226, 234 within the pressure
chamber 176 are in expanded configurations, urging the second chamber
section 196 away from the first chamber section 194 with the result that
the pressure chamber 176 is in an expanded configuration. The spring
constant of the first spring 226 is preferably at least four times
greater than the spring constant of the second spring 234. The spring
constant of the third spring 244 is, in turn, greater than the spring
constant of the first spring 226. With the pressure chamber 176 in this
configuration, the second arms 252 of the control assembly 174 are urged
by the fourth spring 260 towards the position shown in FIG. 9(b), in
which the inner surface of the turbine seal 170 is spaced from the outer
surface of the nose cone 124 to allow air to pass from the air inlet 80
of the turbine chamber 74 to the air duct 82.

[0094] When the vacuum cleaning appliance is switched on, rotation of the
fan unit of the appliance causes a first air flow to be drawn into the
main body 12 of the floor tool 10 through the suction opening 36, and a
second air flow to be drawn into the turbine chamber 74 through the air
inlet 80. As discussed above, the flow of air through the turbine chamber
74 causes the agitator 60 to rotate relative to the main body 12 of the
floor tool 10. The first and second air flows merge within the
entrainment chamber 90 of the air duct 82, and pass through the conduit
14 of the floor tool 10 to the outlet section 94 of the conduit 14.

[0095] As the air is drawn through the floor tool 10, the pressure at the
inlet pipe 270 of the conduit 192 reduces from atmospheric pressure to a
first, relatively low sub-atmospheric pressure. Consequently, the
pressure of the air within the pressure chamber 176 also reduces to this
relatively low pressure. As the air surrounding the pressure chamber 176
remains at or around atmospheric pressure, the pressure difference
between the air within the pressure chamber 176 and the air outside the
pressure chamber 176 generates a force which urges the second chamber
section 196 towards the first chamber section 194.

[0096] The initial movement of the second chamber section 196 towards the
first chamber section 194 causes the end wall 204 of the second chamber
section 196 to move towards the spring retainer 228, against the biasing
force of the second spring 234. The second spring 234 is compressed
between the second chamber section 196 and the spring retainer 228 until
the end wall 204 of the second chamber section 196 engages the spring
retainer 228. Subsequent movement of the second chamber section 196
towards the first chamber section 194 causes the spring retainer 228 to
move along with the second chamber section 196 towards the first chamber
section 194 so that the first spring abutment member 230 engages the
first spring 226. The spring constant of the first spring 226 is selected
so that the first spring 226 is compressible under the action of the
force acting on the second chamber section 196 when the pressure at the
inlet pipe 270 of the conduit 192 is at the first, relatively low
sub-atmospheric pressure, whereas the spring constant of the third spring
244 is selected so that the third spring 244 is relatively incompressible
under the action of the force acting on the second chamber section 196
when the pressure at the inlet pipe 270 of the conduit 192 is at the
first, relatively low sub-atmospheric pressure.

[0097] As the second chamber section 196 moves towards the first chamber
section 194, the pins 236 of the track follower 238 move along the track
222 of the track carrier 214 from the positions P1 shown in FIG. 11(a) to
the positions P2 shown in FIG. 11(b).

[0098] In more detail, and with reference to pin 236a of the pins 236 to
exemplify the movement of all of the pins 236, initially the pin 236a
moves axially, that is, in the direction of the longitudinal axis of the
annular track carrier 214, along the track 222 until the pin 236a abuts a
curved wall 280. As the track follower 238 is rotatable about the track
carrier 214, the pin 236a is able to move along the curved wall 280,
under the action of the force exerted on the second chamber section 196
of the pressure chamber 176, until the pin 236a is in the position P2. In
this position P2, the shape of the track 222 inhibits further axial
movement of the second chamber section 196 towards the first chamber
section 194, and thus prevents the pressure chamber 176 from moving into
a fully contracted configuration. Therefore, while the first, relatively
low sub-atmospheric pressure is sustained at the inlet pipe 270 the pins
236 remain in the positions P2. The control mechanism may thus be
considered to be in a first state which inhibits the movement of the
pressure chamber 176 to the fully contracted configuration.

[0099] FIGS. 12(a) and 12(b) illustrate the configuration of the control
assembly 174 when the pins 236 are in the positions P2. The pressure
chamber 176 is in a first, partially contracted configuration in which
the first annular spring abutment member 230 has engaged the end of the
first spring 226 to partially compress the first spring 226, and the
second spring 234 is fully compressed. With the movement of the second
chamber section 196 towards the first chamber section 194, the first arms
250 of the control assembly 174 move relative to the second arms 252. The
end portion 254 of each of the first arms 250 moves towards the end 264
of its respective slot 258, but does not come into contact with the end
264 of the slot 258 before the pins 236 reach the positions P2 in the
track 222. The biasing force of the fourth spring 260 is selected so that
the second arms 252 do not move with the first arms 250 as the first arms
250 move relative to the second arms 252. Therefore, while the control
assembly 174 is in its first, partially contracted configuration the
inner surface of the turbine seal 170 remains spaced from the outer
surface of the nose cone 124 to permit air flow through the turbine
chamber 74, with the result that the agitator 60 continues to rotate
relative to the main body 12 of the floor tool 10.

[0100] As discussed above, when the floor tool 10 is located on a carpeted
floor surface the wheels 48, 50 are pushed into the fibres of the
carpeted floor surface under the weight of the floor tool 10 and the
force acting downwardly on the floor tool 10 due to the pressure
difference between the air passing through the floor tool 10 and the
external environment. This brings the working edges 42, 44 of the sole
plate 26 into contact with the fibres of the floor surface so that the
fibres are agitated by the working edges 42, 44 as the floor tool 10 is
manoeuvred over the floor surface. The length of the bristles 66 of the
agitator 60 is selected so that as the agitator 60 is rotated by the
turbine assembly 72 the volume swept by the tips of the bristles 66
protrudes downwardly beyond the working edges 42, 44 to ensure that the
bristles 66 can also agitate the fibres of the floor surface.

[0101] When the floor tool 10 is subsequently moved from a carpeted floor
surface on to a hard floor surface, depending on the length of the
bristles 66 it is possible that the bristles 66 could come into contact
with and sweep over the hard floor surface. Depending on the nature of
the hard floor surface, it may be desirable to inhibit the rotation of
the agitator 60 before the floor tool 10 is moved on to the hard floor
surface to prevent scratching or other marking of the floor surface by
the rotating bristles 66, while maintaining the air flow into the main
body 12 through the suction opening 36 to draw dirt and debris into the
floor tool 10.

[0102] As mentioned above, the rotation of the agitator 60 relative to the
main body 12 is inhibited by selectively preventing air flow through the
turbine chamber 74. Inhibiting the air flow through the turbine chamber
74 removes the rotational driving force acting on the impeller 100 of the
turbine assembly 72, which in turn removes the rotational driving force
acting on the agitator 60, thereby causing the agitator 60 to come to
rest.

[0103] The transition of the agitator 60 from an active, rotating state to
an inactive, stationary state is effected by varying temporarily the air
pressure within the pressure chamber 176. This is in turn effected by
varying temporarily the air pressure within the air duct 82, which is
connected to the pressure chamber 176 via the turbine chamber 74 and the
conduit 192. The pressure within the air duct 82 is varied by operating a
valve assembly 300 to admit air from the external environment into a flow
path extending from the outlet section 94 of the conduit 14 of the floor
tool 10 to the fan unit of the vacuum cleaning appliance. As illustrated
in FIG. 13(a), in this embodiment the valve assembly 300 is located on a
handle 302 which is connected to a first end of a wand 304. The floor
tool 10 is connected to the other end of the wand 304. As illustrated in
FIG. 13(b) the handle 302 is connected to a hose 400 of a vacuum cleaning
appliance 402. The appliance 402 includes a separating apparatus 404,
preferably a cyclonic separating apparatus, for removing dirt and dust
from the airflow received from the hose 400, and a fan unit 406 which is
located within a main body 408 of the appliance 402 for drawing the
airflow through the appliance 402.

[0104] With reference also to FIGS. 14(a) to 14(d), the handle 302
comprises a handle body 306 and a handle cover 308 which together define
a handgrip portion 310 configured to be grasped by a user. The handgrip
portion 310 extends between a front tubular section 312 and a rear
section 314 of the handle body 306. The front section 312 of the handle
302 is connectable to the first end of the wand 304, and comprises an air
inlet 316 for receiving an air flow from the wand 304. The handle 302
further comprises a cylindrical rotatable section 318 which is connected
between the front section 312 and the rear section 314 of the handle body
306 for rotation relative thereto. An air outlet 319 of the handle 302
extends outwardly from the side wall of the rotatable section 318 for
connection to the hose 400 for conveying the air flow to the separating
apparatus 404 of the vacuum cleaning appliance 402.

[0105] As discussed in more detail below, the valve assembly 300 comprises
a first valve 320 and a second valve 322. The first valve 320 extends
about and supports the periphery of the second valve 322. The first valve
320 and the second valve 322 are arranged to occlude a relatively large,
first aperture 324 formed in the front section 312 of the handle body
306, preferably beneath the handgrip portion 310 of the handle 302. The
second valve 322 is arranged to occlude a relatively small, second
aperture 326 formed in the first valve 320. As illustrated in FIG. 14(d),
this second aperture 326 is located above the first aperture 324, and so
the second valve 322 may be considered to occlude a relatively small
section of the first aperture 324, while the first valve 320 may be
considered to occlude a relatively large section of the first aperture
324. Each of the apertures 324, 326 is thus arranged to admit atmospheric
air into an air flow passing through the handle 302.

[0106] The valve assembly 300 is operable to move the first valve 320 and
the second valve 322 relative to the handle body 306. As discussed below,
the first valve 320 and the second valve 322 may be moved simultaneously
to expose the first aperture 324, whereas the second valve 322 may be
moved separately from the first valve 320 to expose the second aperture
326. In other words, the second valve 322 may be moved relative to the
first valve 320 between a closed position, in which the second aperture
326 is occluded, and an open position, in which the second aperture 326,
and therefore part of the first aperture 324, is exposed. On the other
hand, the first valve 320 is movable simultaneously with the second valve
322 between a closed position, in which the first aperture 324 is
occluded, and an open position, in which the first aperture 324 is fully
exposed.

[0107] With particular reference now to FIGS. 14(b) and 14(d), the valve
assembly 300 comprises a valve drive mechanism 330 for moving the valves
320, 322 between their closed and open positions. The valve drive
mechanism 330 is located within a housing 332 which is located between
the handle cover 308 and a valve drive cover 334 which is connectable to
the handle cover 308. The valve drive mechanism 330 comprises a first
actuator which in the form of a button 336 which protrudes upwardly and
outwardly from the housing 332. The button 336 is depressible by the user
using the thumb of the hand grasping the handgrip portion 310 of the
handle 302 so as to slide relative to the handgrip portion 310 from a
raised position, as illustrated in FIGS. 14(a) to 14(d), to a lowered
position, as illustrated in FIGS. 15(a) and 15(b). The button 336 is
biased towards the raised position by a first handle spring 338 which has
a first end which engages the button 336 and a second end which engages a
spring abutment member 340 connected to, and preferably integral with,
the handle cover 308.

[0108] The valve drive mechanism 330 further comprises a compound gear 342
which is mounted on a spindle 344 connected to the handle cover 308. A
first set of teeth 346 of the compound gear 342 mesh with a set of teeth
located on a drive rack 348. A latch 350 extends between the button 336
and the drive rack 348 so that the drive rack 348 moves with the button
336 between its raised and lowered positions. A driven rack 352 is
located on the opposite side of the compound gear 342 to the drive rack
348. The driven rack 352 has a set of teeth which mesh with a second set
of teeth 354 of the compound gear 342 so that the drive rack 348 and the
driven rack 352 move in opposite directions with rotation of the compound
gear 342. The driven rack 352 comprises a first valve drive member 356
located at the lower end thereof, and a second valve drive member 358
located at the upper end thereof. The first valve 320 comprises a first
valve ridge 360 which is normally spaced from the first valve drive
member 356. The second valve 322 comprises a second valve ridge 362 which
is urged against the second valve drive member 358 by a second handle
spring 364 extending between the spring abutment member 340 and the
second valve ridge 362.

[0109] To operate the valve assembly 300, the user depresses the button
336 so that the button 336 moves from its raised position towards its
lowered position. The movement of the button 336 towards its lowered
position causes the drive rack 348 to move downwards towards the front
portion 312 of the handle body 306 to rotate the compound gear 342, which
results in the driven rack 352 moving upwards away from the front portion
312 of the handle body 306. As the second valve drive member 358 is in
contact with the second valve ridge 362, the movement of the driven rack
352 causes the second valve 322 to move upwardly away from the second
aperture 326 before the first valve drive member 356 engages the first
valve ridge 360. This movement of the second valve 322 before the first
valve 320 allows a small amount of ambient air to bleed into the handle
302 through the second aperture 326 prior to the movement of the first
valve 320 to expose fully the first aperture 324. The admission of this
ambient air into the handle 302 reduces the pressure difference across
the first valve 320. This in turn reduces the force that acts on the
first valve 320, due to this pressure difference, to urge the first valve
320 against the handle 302, and therefore reduces the force required to
move the first valve 320 away from the handle 302 to expose the first
aperture 324. With continued rotation of the compound gear 342 as the
button 336 moves towards its lowered position, the first valve drive
member 356 engages the first valve ridge 360 to raise the first valve 320
simultaneously with the second valve 322 away from the handle 302, as
illustrated in FIGS. 15(a) and 15(b), to expose fully the first aperture
324 to admit ambient air into the airflow passing through the handle 302.

[0110] When the valve assembly 300 is operated by the user to expose the
first aperture 324, the air pressure within the wand 304 increases, and
so the air pressure within the air duct 82 increases. This means that the
air pressure within the turbine chamber 74, which is in fluid
communication with the air duct 82, also increases, from the first,
relatively low sub-atmospheric pressure to a second, relatively high
sub-atmospheric pressure. This results in an increase in the pressure of
the air within the pressure chamber 176. This in turn results in a
decrease in the force acting on the second chamber section 196, due to a
reduction in the pressure differential between the air within the
pressure chamber 176 and the air outside the pressure chamber 176.

[0111] With reference to FIGS. 11(b) and 11(c), the track 222 of the track
carrier 214 is shaped to allow the pins 236 of the track follower 238 to
move axially away from the positions P2 back towards the positions P1.
The spring constant of the first spring 226 is selected so that the force
of the partially compressed spring 226 is greater than the reduced force
acting on the second chamber section 196 so that the first spring 226 is
able to urge the second chamber section 196 away from the first chamber
section 194 towards its expanded configuration. Consequently, and with
reference also to FIG. 16(a), under the biasing force of the first spring
226 the spring retainer 228 and the second chamber section 196 are moved
away from the first chamber section 194 until the annular end of the
spring retainer 228 engages the lugs of the retainer clip 235. This
prevents further movement of the spring retainer 228 away from the first
chamber section 194. On the other hand, the spring constant of the second
spring 234 is selected so that the force of the compressed second spring
234 is smaller than the reduced force acting on the second chamber
section 196, and so the second spring 234 remains in its compressed
configuration with the second chamber section 196 urged against the
spring retainer 228. The pressure chamber 176 may be considered to have
moved from the first, partially contracted configuration, as shown in
FIG. 12(a) to a second, partially contracted configuration, as shown in
FIG. 16(a).

[0112] As the pins 236 move away from the positions P2, each pin 236
engages an inclined wall 282 of the track 222, and moves along the wall
282 through rotational and axial movement of the track follower 238
relative to the track carrier 214. When the movement of the track
follower 238 relative to the track carrier 214 has stopped, due to the
engagement of the end of the spring retainer 228 with the lugs of the
retainer clip 235, the pins 236 are in the positions P3 shown in FIG.
11(c). As shown in FIG. 16(b), the movement of the second chamber section
196 away from the first chamber section 194 does not result in any
movement of the second arms 252 relative to the turbine assembly 72, as
the end portion 254 of each of the first arms 250 remains spaced from the
ends of its respective slot 258. The air path through the turbine chamber
74 remains open, and so the impeller 100 of the turbine assembly 72
continues to rotate to drive the rotation of the agitator 60. However,
the control mechanism has now changed to a second state which allows the
pressure chamber 176 to move to a fully contracted configuration, as
discussed below.

[0113] In this embodiment, the valve 320 remains in its open position
while the user depresses the button 336. When the button 336 is released
by the user, the first handle spring 338 urges the button 336 towards its
raised position, while the second handle spring 364 urges the second
valve ridge 362 and the driven rack 352 downwardly towards the front
portion 312 of the handle body 306. This results in the reverse rotation
of the compound gear 342. The downward movement of the driven rack 352
first brings the first valve 320 into contact with the front section 312
of the handle body 306 to occlude partially the first aperture 324, and
subsequently brings the second valve 322 into contact with the first
valve 320 to occlude the second aperture 326, and thereby occlude fully
the first aperture 324. The force of the second handle spring 364 urges
the second valve 322 against the first valve 320 to maintain an air-tight
seal between the second valve 322 and the first valve 320, and between
the first valve 320 and the front section 312 of the handle body 306. The
springs 338, 364 are preferably arranged so that the movement of the
valves 320, 322 from their open positions to their closed positions takes
several seconds so as to allow the second, relatively high
sub-atmospheric pressure to be established in the air duct 82 before the
apertures 324, 326 are occluded by the valves 320, 322.

[0114] With the first aperture 324 occluded by the valves 320, 322, the
air pressure within the air duct 82 decreases so that the air pressure
within the turbine chamber 74 and the pressure chamber 176 returns to the
first, relatively low sub-atmospheric pressure. As a result, the force
acting on the second chamber section 196, due to the pressure
differential between the air within the pressure chamber 176 and the air
outside the pressure chamber 176, increases back to the level prior to
the operation of the valve assembly 300. As mentioned above, the spring
constant of the first spring 226 is selected so that the force of the
partially compressed first spring 226 is lower than the increased force
acting on the second chamber section 196. Therefore, with reference to
FIG. 17(a), under the action of the force acting on the second chamber
section 196 the spring retainer 228 and the second chamber section 196
are urged towards the first chamber section 194 against the biasing force
of the first spring 226.

[0115] With reference also to FIGS. 11(c) and 11(d), the track 222 of the
track carrier 214 is shaped to allow the pins 236 of the track follower
238 to move axially away from the positions P3. Under the action of the
increased force applied to the second chamber section 196, as the pins
236 move away from the positions P3 each pin 236 engages an inclined wall
284 of the track 222, and moves along the wall 284, through rotational
and axial movement of the track follower 238 relative to the track
carrier 214, as the second chamber section 196 is pushed towards the
first chamber section 194. At the end of the wall 284, each pin 236
enters an axially extending slot 286 of the track 222 which allows the
pins 236 to move rapidly along the track carrier 214.

[0116] With the movement of the second chamber section 196 towards the
first chamber section 194, the end portions of the first arms 250 move
along the slots 258 so as to each engage the end 264 of its respective
slot 258. The spring constant of the fourth spring 260 is selected so
that the force of the fourth spring 260 is lower than the increased force
acting on the second chamber section 196. Therefore, with reference to

[0117] FIGS. 17(a) and 17(b), under the action of the force acting on the
second chamber section 196 the fourth spring 260 is compressed to allow
the second arms 252 to be pulled towards the pressure chamber 176 by the
first arms 250 of the second chamber section 196 as the second chamber
section 196 continues to be pushed towards the first chamber section 194.
The movement of the second arms 252 towards the pressure chamber 176
causes the annular member 172 of the control assembly 174 to move towards
the turbine assembly 72 until the inner surface of the seal 170 engages
the outer surface of the nose cone 124, as shown in FIG. 17(a). The
contact of the inner surface of the seal 170 with the outer surface of
the nose cone 124 prevents further movement of the second chamber section
196 towards the first chamber section 194. The pressure chamber 176 may
therefore be considered to be in a fully contracted configuration when
the inner surface of the seal 170 engages the outer surface of the nose
cone 124. When the pressure chamber 176 is in this fully contracted
configuration, the first spring 226, the second spring 234 and the fourth
spring 260 are all in fully compressed configurations, and the pins 236
of the track follower 238 are in the positions P4 illustrated in FIG.
11(d), in which each pin 236 is located towards the end of a respective
slot 286 of the track 222. The third spring 244 remains in an expanded
configuration.

[0118] The engagement between the inner surface of the seal 170 and the
outer surface of the nose cone 124 closes the annular channel between the
stator body 114 and the stator housing 120, thereby inhibiting air flow
through the turbine chamber 74. The lack of an air flow through the
turbine chamber 74 removes the driving force applied to the impeller
blades 104, and so the rotational speed of the impeller 100, and
therefore that of the agitator 60, decreases gradually to zero. The
pressure differential across the seal 170 generates a force which urges
the seal 170 against the nose cone 124, against the internal bias of the
seal 170, to prevent air flow through the turbine chamber 74.

[0119] To re-start the rotation of the agitator 60 relative to the main
body 12, the user operates the valve assembly 300 to admit air from the
external environment into the flow path. The admission of air into the
flow path increases the air pressure within the air duct 82, which in
turn increases the air pressure within the turbine chamber 74 and the
pressure chamber 176 which are both connected to the air duct 82. The
increase in the air pressure within the turbine chamber 74 reduces the
force acting on the seal 170 due to the pressure differential across the
seal 170, whereas the increase in the air pressure within the pressure
chamber 176 reduces the force urging the second chamber section 196
towards the outer chamber 194, which in turn reduces the force which is
applied to the seal 170 by the driving mechanism 174. The reduction in
the forces acting on the seal 170 enables the fourth spring 260 to return
the seal 170 rapidly to its expanded configuration in which the inner
surface of the seal 170 is spaced from the nose cone 124. This allows an
air flow to pass through the turbine chamber 74 towards the air duct 82
to drive the rotation of the impeller 100 within the turbine chamber 74,
and thus drive the rotation of the agitator 60 within the main body 12.

[0120] The return of the seal 170 to its expanded configuration is not
inhibited by the control assembly 174. The movement of the fourth spring
260 to its expanded configuration causes the second arms 252 to pull the
first arms 250 towards the turbine assembly 72, which in turn causes the
first arms 250 to pull the second chamber section 196 away from the first
chamber section 194 against the reduced force acting on the second
chamber section 196 due to the pressure differential between the air
within the pressure chamber 176 and the air outside the pressure chamber
176. As the pins 236 are located towards the ends of the slots 286 of the
track 222, the pins 236 are free to move unimpeded along the slots 286
away from the positions P4.

[0121] With air flowing through the turbine chamber 74, the pressure
within the turbine chamber 74 returns to the second, relatively high
sub-atmospheric pressure. As discussed above, the reduction in the force
acting on the second chamber section 196 allows the force of the first
spring 226 to return the pressure chamber 176 to its second, partially
contracted configuration, as shown in FIG. 16(a), in which the annular
end of the spring retainer 228 engages the lugs of the retainer clip 235.
With reference to FIGS. 11(d) and 11(e), as the pressure chamber 176 is
returned to this configuration each pin 236 of the track follower 238
moves axially along a respective slot 286 until the pin 236 engages a
respective inclined wall 288 of the track 222. Through a combination of
axial and rotational movement of the track follower 238 relative to the
track carrier 214, the pins 236 move along the walls 288. At the end of
the wall 288, each pin 236 enters an axially extending slot 290 of the
track 222 which allows the pins 236 to move along the track 222 to the
positions P5. The pins 236 do not move beyond the positions P5 due to the
engagement of the lugs of the retainer clip 235 with the end of the
spring retainer 228. The positions P5 are spaced circumferentially from
the positions P3, and are each located in a path, extending between a
position P1 and a position P2, along which one of the pins 236 moved when
the vacuum cleaning appliance was first switched on. The control
mechanism may be considered to have returned to its first state which
prevents the pressure chamber 176 from moving to its fully contracted
configuration. However, each pin 236 is now located within a different
track section from that in which that pin 236 was located when the
appliance was first switched on.

[0122] As discussed above, when the button 336 is released by the user the
valves 320, 322 move to occlude the apertures 324, 326 so that the air
pressure within the air duct 82 returns to the first, relatively low
sub-atmospheric pressure. As a result, the force acting on the second
chamber section 196, due to the pressure differential between the air
within the pressure chamber 176 and the air outside the pressure chamber
176, increases back to the level prior to the operation of the valve
assembly 300. As mentioned above, the spring constant of the first spring
226 is selected so that the force of the partially compressed first
spring 226 is lower than the increased force acting on the second chamber
section 196. Therefore, under the action of the force acting on the
second chamber section 196 the spring retainer 228 and the second chamber
section 196 are urged towards the first chamber section 194 against the
biasing force of the first spring 226 so that the pins 236 move to the
positions P2 illustrated in FIG. 11(b) and the pressure chamber 176
returns to its first, partially contracted configuration illustrated in
FIG. 12(a). The seal 170 is maintained in its expanded configuration, and
so the air flow is maintained through the turbine chamber 74.

[0123] Thus, the agitator 60 may be easily toggled between an active,
rotating state and an inactive, stationary state as required by the user
through simply operating the valve assembly 300.

[0124] During use, the second valve 322 may be moved to an open position
in isolation from the first valve 320. This can enable the pressure at
the suction opening 36 to be increased to a level which enables the floor
tool 10 to be used to clean curtains or other loose fabric without that
fabric becoming trapped within the main body 12 of the floor tool. To
open the second valve 322, the user operates a second actuator to move
the second valve 322 away from the second aperture 326. In this
embodiment, the second actuator is in the form of a trigger 370 located
beneath the handgrip portion 310 of the handle 302, and which is attached
to the second valve 322. The trigger 370 may be pulled by the user using
a finger of the hand which is grasping the handle 302 to move the second
valve 322 away from the second aperture 326 against the biasing force of
the second handle spring 364. Due to the support of the periphery of the
second valve 322 by the first valve 320, pulling the second valve 322
away from the second aperture 326 does not cause the first valve 320 to
move away from the first aperture 324. For example, the first valve 320
may be provided with inclined support surfaces for supporting the second
valve 322, and which allow the second valve 322 to move away from the
first valve 320 without dragging the first valve 320 away from the first
aperture 324.

[0125] When the cleaning of the fabric has been completed, the user
releases the trigger 370 to allow the second handle spring 364 to return
the second valve 322 automatically to its closed position. As the second
aperture 326 is smaller than the first aperture 324, the exposure of only
the second aperture 326 to the atmosphere is insufficient to raise the
pressure within the turbine chamber 74 to the second, relatively high
sub-atmospheric pressure and thus actuate a change in the state of the
agitator 60.

[0126] When the user switches off the vacuum cleaning appliance, the
pressure in the air duct 82, and therefore the air pressure within the
pressure chamber 176, returns to atmospheric pressure, thereby removing
the force which otherwise urges the second chamber section 196 towards
the first chamber section 194. Under the biasing force of the springs
226, 234 the pressure chamber 176 is urged towards its expanded
configuration. If the agitator 60 is rotating when the vacuum cleaning
appliance is switched off, the pins 236 move, with both axial and
rotational movement of the track follower 238 relative to the track
carrier 214, from positions P2 to positions P3 under the biasing force of
the first spring 226, and then from the positions P3 to the positions P1
under the biasing force of the second spring 234. The position P1 to
which each pin 236 returns is not necessarily the same position P1 as
that pin 236 was in when the appliance was first switched on, as this
depends on the number of times that the agitator 60 has been placed in an
inactive state during use of the appliance.

[0127] If, on the other hand, the agitator 60 is stationary when the
vacuum cleaning appliance is switched off, the pins 236 move, again with
both axial and rotational movement of the track follower 238 relative to
the track carrier 214, from positions P4 to positions P5 under the
biasing force of the first spring 226, and then from the positions P5 to
the positions P1 under the biasing force of the second spring 234. Again,
the position P1 to which each pin 236 returns is not necessarily the same
position P1 as that pin 236 was in when the appliance was first switched
on.

[0128] The return of the pins 236 of the track follower 238 to the
positions P1 maintains the control mechanism in its first state.
Consequently, when the vacuum cleaning appliance is switched off the
control assembly 174 will adopt a configuration in which an air flow is
drawn through the turbine chamber 74 to rotate the agitator 60 when the
appliance is next switched on, irrespective of the state of the agitator
60 when the appliance was switched off.

[0129] During operation of the vacuum cleaning appliance, and while the
agitator 60 is in an active state, the control assembly 174 is in the
configuration illustrated in FIGS. 12(a) and 12(b), and the pressure
chamber 176 is in the first, partially contracted configuration. Rotation
of the fan unit of the appliance causes a first air flow to be drawn into
the main body 12 of the floor tool 10 through the suction opening 36, and
a second air flow to be drawn into the turbine chamber 74 through the air
inlet 80. The first air flow passes through the main body 12 to the air
outlet 86 of the main body 12, and enters the air duct 82 from the air
inlet 84. The second air flow passes through the turbine chamber 74 and
enters the air duct 82 from the side inlet 88.

[0130] In the event that the airflow path through the main body 12 becomes
blocked in some way, such as by an object becoming trapped in the ducting
or by the suction opening 36 becoming sealed against a surface, an
increased amount of air will flow through the turbine chamber 74. This
increase in airflow will increase the speed of rotation of the impeller
100, and in turn increase the speed of rotation of the agitator 60. In
such a circumstance, the control assembly 174 operates in response to the
increased airflow through the turbine chamber 74 to inhibit rotation of
the impeller 100 and so prevent damage to components of the drive
mechanism 70, for example the bearings 116, 118 or the belts 142, 158,
due to the increased rotational speed of the impeller 100.

[0131] The increased airflow through the turbine chamber 74 reduces the
air pressure within the turbine chamber to a third sub-atmospheric
pressure which is lower than the first, relatively low sub-atmospheric
pressure. The reduction in the air pressure within the turbine chamber 74
reduces the air pressure within the pressure chamber 176, which increases
the pressure difference between the air within the pressure chamber 176
and the air outside the pressure chamber 176. This in turn increases the
force urging the second chamber section 196 towards the first chamber
section 194. This increased force acting on the second chamber section
196 causes the second chamber section 196 to move towards the first
chamber section 194, against the biasing force of the third spring 244,
as illustrated in FIG. 18(a). Due to the location of the pins 236 of the
track follower 238 in the positions P2, the track follower 238 and the
annular disc 242 remain in a fixed position relative to the track 222,
but the retaining ring 240, which is connected to the second chamber
section 196, moves away from the track follower 238 as the second chamber
section 196 moves towards the first chamber section 194. FIG. 18(a)
illustrates the pressure chamber 176 in a second, fully contracted
configuration.

[0132] As discussed above in connection with FIGS. 17(a) and 17(b), the
second arms 252 are pulled towards the pressure chamber 176 by the first
arms 250 of the second chamber section 196 as the second chamber section
196 is urged towards the first chamber section 194. The movement of the
second arms 252 towards the pressure chamber 176 causes the annular
member 172 of the control assembly 174 to move towards the turbine
assembly 72 until the inner surface of the seal 170 engages the outer
surface of the nose cone 124, as shown in FIG. 18(a). The engagement
between the inner surface of the seal 170 and the outer surface of the
nose cone 124 closes the annular channel between the stator body 114 and
the stator housing 120, thereby inhibiting air flow through the turbine
chamber 74. The lack of an air flow through the turbine chamber 74
removes the driving force applied to the impeller blades 104, and so the
rotational speed of the impeller 100, and therefore that of the agitator
60, decreases gradually to zero.

[0133] When the agitator 60 has stopped rotating, the user may switch off
the vacuum cleaning appliance to allow the blockage to be removed. When
the appliance is switched off, the pressure in the air duct 82, and
therefore the air pressure within the pressure chamber 176, returns to
atmospheric pressure, thereby removing the force which otherwise urges
the second chamber section 196 towards the first chamber section 194.
Under the biasing force of the springs 226, 234, 244, 260, the pressure
chamber 176 is urged towards its expanded configuration. The pins 236
move, with both axial and rotational movement of the track follower 238
relative to the track carrier 214, from positions P2 to positions P3
under the biasing force of the first spring 226, and then from the
positions P3 to the positions P1 under the biasing force of the second
spring 234. The return of the pins 236 of the track follower 238 to the
positions P1 returns the control mechanism to its first state so that an
air flow is drawn through the turbine chamber 74 to rotate the agitator
60 when the appliance is next switched on.